Clinical features and prognosis of extragastrointestinal stromal tumors

Objective: To investigate the prognostic factors of extragastrointestinal stromal tumors (EGISTs). Methods: A retrospective analysis of the clinical data of 464 gastrointestinal stromal tumor (GIST) cases and 22 EGIST cases that underwent surgical treatment at our hospital during the period of 1999-2011 and that received pathological confirmation was conducted. The Kaplan-Meier method was adopted for survival analysis, and the Cox proportional hazards model was used for multivariate regression analysis. Results: The 1-, 3-, and 5-year overall survival rates of EGIST were 91.7%, 61.1% and 48.9%, respectively; the 1-, 3-, and 5-year recurrence-free survival rates were 72.2%, 28.9% and 19.3%, respectively. The overall survival rate of EGIST was significantly lower than that of GIST (with 1-, 3-, 5-year overall survival rates of 94.0%, 88.1%, and 82.4%, respectively; P = 0.008), but EGIST and GIST did not show a statistically significant difference in recurrence-free survival (P = 0.299). Kaplan-Meier univariate analysis revealed that the primary tumor site, tumor size, and tumor cell nuclear pleomorphism are important factors affecting the overall survival of EGIST patients after surgery. Multivariate analysis did not identify independent risk factors affecting the prognosis of EGIST patients. Conclusion: Compared with GIST patients, EGIST patients had a lower disease onset age, relatively larger tumors and a poorer prognosis. Survival analysis showed that the primary tumor site, tumor size, and tumor cell nuclear pleomorphism are important prognostic factors for patients with EGIST.